The K4AAG045WD-4CRB chips include four stacked dies using through silicon vias (TSVs) for vertical interconnect. Our lab’s initial X-ray analysis confirms the DDR4 SDRAM is indeed a four-die stack. A quick decap of one of the parts revealed die markings of K4A4G085WD, corresponding to Samsung’s 4 Gb D-die DDR4 SDRAM.